As skyscrapers and indoor rooms become more diversified, there are shadow areas having poor radio environments in wireless communication systems in buildings. The wireless communication system has deteriorated radio transceiving environments in a vehicle of which a body is made of metal.
As one of techniques for dealing with such a disadvantage, the poor radio environment is improved by using a repeater. The techniques using the repeater is configured to improve radio environments by using a positive repeater using two antennas and a bi-direction or duplex amplifying circuit disposed between the two antennas or a passive repeater configured to connect two antennas with each other via a coaxial cable or a waveguide.
More specifically, an antenna is installed outside a building or vehicle and connected with a reradiation antenna which is installed in the building or vehicle via a waveguide or coaxial cable, so as to improve the radio environment of a shadow area.
However, the technique using the repeater radiating an electromagnetic wave and is likely to affect peripheral electronic devices. Especially, in case electronic equipments are intensively installed in a building or vehicle, other devices might be affected disadvantageously. Also, it is difficult to apply the technique using the repeater to diverse communication standards having different-bands frequencies.
Accordingly, there are increasing demands for developments of an antenna which may improve communication environments, without such the disadvantages.